Artificial satellite with an orbit having a long staying time in a zenith direction, an orbit control method and a communication system therewith

A communication terminal for communicating through an artificial satellite, wherein the artificial satellite is placed into an orbit in which an individual satellite orbits on an elliptical orbit so that at least one of the artificial satellites is always viewable within a pre-defined range of operational elevational angle in a zenith direction from a service area. A group of the artificial satellites are satellites on respective orbits obtained by combining an inclination angle and an eccentricity squared of said elliptical orbit so that a time period during which an artificial satellite is viewable from ground is substantially identical and the communication terminal has a transmitter and receiver for transmitting and receiving a signal through the group of artificial satellites.